hwmon: Add support for LTC4151 (de779015) · Commits · e / devices / android_kernel_fairphone_FP5

Documentation/hwmon/ltc4151

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		Kernel driver ltc4151
		=====================

		Supported chips:
		* Linear Technology LTC4151
		Prefix: 'ltc4151'
		Addresses scanned: -
		Datasheet:
		http://www.linear.com/docs/Datasheet/4151fc.pdf

		Author: Per Dalen <per.dalen@appeartv.com>


		Description
		-----------

		The LTC4151 is a High Voltage I2C Current and Voltage Monitor.


		Usage Notes
		-----------

		This driver does not probe for LTC4151 devices, since there is no register
		which can be safely used to identify the chip. You will have to instantiate
		the devices explicitly.

		Example: the following will load the driver for an LTC4151 at address 0x6f
		on I2C bus #0:
		# modprobe ltc4151
		# echo ltc4151 0x6f > /sys/bus/i2c/devices/i2c-0/new_device


		Sysfs entries
		-------------

		Voltage readings provided by this driver are reported as obtained from the ADIN
		and VIN registers.

		Current reading provided by this driver is reported as obtained from the Current
		Sense register. The reported value assumes that a 1 mOhm sense resistor is
		installed.

		in1_input VDIN voltage (mV)

		in2_input ADIN voltage (mV)

		curr1_input SENSE current (mA)

drivers/hwmon/Kconfig

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		@@ -636,6 +636,17 @@ config SENSORS_LM93
		This driver can also be built as a module. If so, the module
		will be called lm93.

		config SENSORS_LTC4151
		tristate "Linear Technology LTC4151"
		depends on I2C
		default n
		help
		If you say yes here you get support for Linear Technology LTC4151
		High Voltage I2C Current and Voltage Monitor interface.

		This driver can also be built as a module. If so, the module will
		be called ltc4151.

		config SENSORS_LTC4215
		tristate "Linear Technology LTC4215"
		depends on I2C && EXPERIMENTAL

drivers/hwmon/Makefile

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		@@ -80,6 +80,7 @@ obj-$(CONFIG_SENSORS_LM90) += lm90.o
		obj-$(CONFIG_SENSORS_LM92) += lm92.o
		obj-$(CONFIG_SENSORS_LM93) += lm93.o
		obj-$(CONFIG_SENSORS_LM95241) += lm95241.o
		obj-$(CONFIG_SENSORS_LTC4151) += ltc4151.o
		obj-$(CONFIG_SENSORS_LTC4215) += ltc4215.o
		obj-$(CONFIG_SENSORS_LTC4245) += ltc4245.o
		obj-$(CONFIG_SENSORS_LTC4261) += ltc4261.o

drivers/hwmon/ltc4151.c

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		/*
		* Driver for Linear Technology LTC4151 High Voltage I2C Current
		* and Voltage Monitor
		*
		* Copyright (C) 2011 AppearTV AS
		*
		* Derived from:
		*
		* Driver for Linear Technology LTC4261 I2C Negative Voltage Hot
		* Swap Controller
		* Copyright (C) 2010 Ericsson AB.
		*
		* Datasheet: http://www.linear.com/docs/Datasheet/4151fc.pdf
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License as published by
		* the Free Software Foundation; either version 2 of the License, or
		* (at your option) any later version.
		*
		* This program is distributed in the hope that it will be useful,
		* but WITHOUT ANY WARRANTY; without even the implied warranty of
		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		* GNU General Public License for more details.
		*
		* You should have received a copy of the GNU General Public License
		* along with this program; if not, write to the Free Software
		* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
		*
		*/

		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/init.h>
		#include <linux/err.h>
		#include <linux/slab.h>
		#include <linux/i2c.h>
		#include <linux/hwmon.h>
		#include <linux/hwmon-sysfs.h>

		/* chip registers */
		#define LTC4151_SENSE_H 0x00
		#define LTC4151_SENSE_L 0x01
		#define LTC4151_VIN_H 0x02
		#define LTC4151_VIN_L 0x03
		#define LTC4151_ADIN_H 0x04
		#define LTC4151_ADIN_L 0x05

		struct ltc4151_data {
		struct device *hwmon_dev;

		struct mutex update_lock;
		bool valid;
		unsigned long last_updated; /* in jiffies */

		/* Registers */
		u8 regs[6];
		};

		static struct ltc4151_data ltc4151_update_device(struct device dev)
		{
		struct i2c_client *client = to_i2c_client(dev);
		struct ltc4151_data *data = i2c_get_clientdata(client);
		struct ltc4151_data *ret = data;

		mutex_lock(&data->update_lock);

		/*
		* The chip's A/D updates 6 times per second
		* (Conversion Rate 6 - 9 Hz)
		*/
		if (time_after(jiffies, data->last_updated + HZ / 6) \|\| !data->valid) {
		int i;

		dev_dbg(&client->dev, "Starting ltc4151 update\n");

		/* Read all registers */
		for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
		int val;

		val = i2c_smbus_read_byte_data(client, i);
		if (unlikely(val < 0)) {
		dev_dbg(dev,
		"Failed to read ADC value: error %d\n",
		val);
		ret = ERR_PTR(val);
		goto abort;
		}
		data->regs[i] = val;
		}
		data->last_updated = jiffies;
		data->valid = 1;
		}
		abort:
		mutex_unlock(&data->update_lock);
		return ret;
		}

		/* Return the voltage from the given register in mV */
		static int ltc4151_get_value(struct ltc4151_data *data, u8 reg)
		{
		u32 val;

		val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4);

		switch (reg) {
		case LTC4151_ADIN_H:
		/* 500uV resolution. Convert to mV. */
		val = val * 500 / 1000;
		break;
		case LTC4151_SENSE_H:
		/*
		* 20uV resolution. Convert to current as measured with
		* an 1 mOhm sense resistor, in mA.
		*/
		val = val * 20;
		break;
		case LTC4151_VIN_H:
		/* 25 mV per increment */
		val = val * 25;
		break;
		default:
		/* If we get here, the developer messed up */
		WARN_ON_ONCE(1);
		val = 0;
		break;
		}

		return val;
		}

		static ssize_t ltc4151_show_value(struct device *dev,
		struct device_attribute da, char buf)
		{
		struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
		struct ltc4151_data *data = ltc4151_update_device(dev);
		int value;

		if (IS_ERR(data))
		return PTR_ERR(data);

		value = ltc4151_get_value(data, attr->index);
		return snprintf(buf, PAGE_SIZE, "%d\n", value);
		}

		/*
		* Input voltages.
		*/
		static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, \
		ltc4151_show_value, NULL, LTC4151_VIN_H);
		static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, \
		ltc4151_show_value, NULL, LTC4151_ADIN_H);

		/* Currents (via sense resistor) */
		static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, \
		ltc4151_show_value, NULL, LTC4151_SENSE_H);

		/* Finally, construct an array of pointers to members of the above objects,
		* as required for sysfs_create_group()
		*/
		static struct attribute *ltc4151_attributes[] = {
		&sensor_dev_attr_in1_input.dev_attr.attr,
		&sensor_dev_attr_in2_input.dev_attr.attr,

		&sensor_dev_attr_curr1_input.dev_attr.attr,

		NULL,
		};

		static const struct attribute_group ltc4151_group = {
		.attrs = ltc4151_attributes,
		};

		static int ltc4151_probe(struct i2c_client *client,
		const struct i2c_device_id *id)
		{
		struct i2c_adapter *adapter = client->adapter;
		struct ltc4151_data *data;
		int ret;

		if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
		return -ENODEV;

		data = kzalloc(sizeof(*data), GFP_KERNEL);
		if (!data) {
		ret = -ENOMEM;
		goto out_kzalloc;
		}

		i2c_set_clientdata(client, data);
		mutex_init(&data->update_lock);

		/* Register sysfs hooks */
		ret = sysfs_create_group(&client->dev.kobj, &ltc4151_group);
		if (ret)
		goto out_sysfs_create_group;

		data->hwmon_dev = hwmon_device_register(&client->dev);
		if (IS_ERR(data->hwmon_dev)) {
		ret = PTR_ERR(data->hwmon_dev);
		goto out_hwmon_device_register;
		}

		return 0;

		out_hwmon_device_register:
		sysfs_remove_group(&client->dev.kobj, &ltc4151_group);
		out_sysfs_create_group:
		kfree(data);
		out_kzalloc:
		return ret;
		}

		static int ltc4151_remove(struct i2c_client *client)
		{
		struct ltc4151_data *data = i2c_get_clientdata(client);

		hwmon_device_unregister(data->hwmon_dev);
		sysfs_remove_group(&client->dev.kobj, &ltc4151_group);

		kfree(data);

		return 0;
		}

		static const struct i2c_device_id ltc4151_id[] = {
		{ "ltc4151", 0 },
		{ }
		};
		MODULE_DEVICE_TABLE(i2c, ltc4151_id);

		/* This is the driver that will be inserted */
		static struct i2c_driver ltc4151_driver = {
		.driver = {
		.name = "ltc4151",
		},
		.probe = ltc4151_probe,
		.remove = ltc4151_remove,
		.id_table = ltc4151_id,
		};

		static int __init ltc4151_init(void)
		{
		return i2c_add_driver(&ltc4151_driver);
		}

		static void __exit ltc4151_exit(void)
		{
		i2c_del_driver(&ltc4151_driver);
		}

		MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
		MODULE_DESCRIPTION("LTC4151 driver");
		MODULE_LICENSE("GPL");

		module_init(ltc4151_init);
		module_exit(ltc4151_exit);